Pressure control valve unit for hydraulic brake device

Abstract

A pressure control valve unit for a hydraulic brake device is provided which considerably reduces noise, vibration, and harshness, and is compact and inexpensive. The pressure control valve unit comprises a switching valve and a normally-open inlet valve sequentially located in the main brake line in a housing cavity between the master cylinder and the wheel cylinder(s). During a brake pressure control action, the difference in pressure acting on the master cylinder side and that on the wheel cylinder side causes the switching valve to switch to a constricted channel, thereby noticeably reducing the amount of noise vibration harshness.

What is claimed is: 
     
       1. A pressure control valve unit for a hydraulic brake device comprising: a normally-openinlet valve, said inlet valve located in a housing cavity in a main brake line between a master cylinder and one or more wheel cylinder;   a switch valve having a wide channel and a constricted channel, said switching valve located in said housing cavity in the main brake line between the master cylinder and the inlet valve; and   a piston having an internal switching valve seat for the switching valve, wherein said piston is energized by a spring in the direction of a normally-open valve and keeping the wide channel for said switching valve;   wherein said switching valve routes brakes fluid through the wide channel and the constricted channel during normal operation, and switches during a brake pressure control operation with a pressure differential between the master cylinder side and the wheel cylinder side to route brake fluid through the constricted channel.   
     
     
       2. The pressure control valve unit of claim 1, wherein the inlet valve further comprises: a sleeve affixed to the housing cavity; an armature slidably housed within the sleeve and having integrally molded inlet valve plug; a magnetic core affixed to the housing cavity having integrally molded on it an inlet valve seat and a small-diameter segment through which the inlet valve plug passes; and a coil assembly that operates the armature mounted around the sleeve;   wherein said magnetic core comprises a switching valve plug and a constricted channel molded on the tip of the small-diameter segment; and   wherein said piston is mounted externally around said small-diameter segment of the magnetic core and divides said housing cavity into a primary pressure chamber, with passage to the master cylinder, and a secondary pressure chamber, with passage to each wheel cylinder.   
     
     
       3. The pressure control valve unit of claim 2, wherein the piston slides such that the switching valve closes and switches to a constricted channel when the difference between the pressure acting on the primary pressure chamber with passage to the master cylinder and on the secondary pressure chamber with passage to a wheel cylinder exceeds a threshold value. 
     
     
       4. The pressure control valve unit of claim 2, wherein a notched groove forming a constricted channel is molded on the switching valve seat. 
     
     
       5. The pressure control valve unit claim 2, wherein in a notched groove forming a constricted channel is molded around the external circumference of the switching valve plug. 
     
     
       6. The pressure control valve unit of claim 2, wherein a groove molded between the bottom face of the housing cavity and the end face of the piston is formed to provide constant passage between the main brake line on the master cylinder side and the primary pressure chamber. 
     
     
       7. The pressure control valve unit of claim 2, wherein a small cavity bored on the side face of the piston is formed to provide constant passage between the main brake line on the master cylinder side and the primary pressure chamber. 
     
     
       8. The pressure control valve unit of claim 2, wherein a seal is mounted externally around said piston to form a release channel that allows brake fluid between the housing cavity and the circumference of the piston to flow only from the secondary pressure chamber to the primary pressure chamber. 
     
     
       9. The pressure control valve unit of claim 3, wherein: a notched groove forming a constricted channel is molded on the switching valve seat;   a groove molded between the bottom face of the housing cavity and the end face of the piston is formed to provide constant passage between the main brake line on the master cylinder side and the primary pressure chamber; and   a seal is mounted externally around said piston to form a release channel that allows brake fluid between the housing cavity and the circumference of the piston to flow only from the secondary pressure chamber to the primary pressure chamber.   
     
     
       10. The pressure control valve unit of claim 3, wherein: a notched groove forming a constricted channel is molded around the external circumference of the switching valve plug;   a groove molded between the bottom face of the housing cavity and the end face of the piston is formed to provide constant passage between the main brake line on the master cylinder side and the primary pressure chamber; and   a seal is mounted externally around said piston to form a release channel that allows brake fluid between the housing cavity and the circumference of the piston to flow only from the secondary pressure chamber to the primary pressure chamber.